The development of wind generators depends on the energy they produce, this means the elements they are made up of need to be larger as they are subject to greater external loads, so their service life decreases and at the same time their cost clearly rises.
One of the elements that is mostly affected by this is power train, which includes the multiplier unit, the high speed shaft and the generator and especially, the low speed shaft, responsible for coupling the rotor with the multiplier unit.
We will comment on several couplings known in the technique to join the rotor of the wind generator with the elements of its power train.
At a theoretical level, in “Electrical Energy Propipeion Wind Systems” (Sistemas Eólicos de Energia Eléctrica) by J. L. Rodriguez Amedo, J. C. Burgos Diaz and S. Arnalte Gómez (Ed. Rueda S. L., Madrid 2003), three types of couplings are mentioned between the rotor shaft and the multiplier unit:                By means of support of the rotor shaft on two bearings which are separated one from the other and fitted to the base of the nacelle, in a way that all the unwanted forces are transmitted to the tower, and the multiplier unit only supports the torque transmitted by the rotor blades. In this type of configuration, an elastic disc is normally used in the coupling between the rotor shaft and the multiplier unit to absorb the slight misalignments between them.        By means of support of the rotor shaft on only one bearing integral to the base of the nacelle and another support on a bearing integrated in the multiplier unit, and in this way using an elastic disc in the coupling between the rotor shaft and the multiplier unit. This way the loads transmitted to the tower are reduced as the distance between the bearings can be minimised. Still, in these two first configurations, the rotor shaft is subject to stressful bending moments which imply very strong designs of the components of the power train, and even needing torque arms in the multiplier unit to absorb the transmitted loads.        With the rotor shaft joined to a fixed support connected to the tower by means of a flange, whose purpose is to absorb the bending moments transmitted by the rotor.        
There are also couplings between the rotor shaft and the multiplier unit in patent documents as shown below:
Patent application WO9611338 describes, according to its FIGS. 1 and 2, the couplings used in the known turbines. According to FIG. 1, the rotor shaft is placed onto two bearings directly supported by the nacelle as well as a third bearing placed in the multiplier unit. According to FIG. 2, the rotor shaft is placed onto two bearings directly supported by the nacelle which means a high transmission of unwanted forces to the multiplier unit.
Patent application WO02079644 describes a turbine in which the multiplier unit is directly coupled to the hub, in this way doing without the rotor shaft.
Patent application WO03031811 describes a coupling mechanism in which the rotor shaft is supported on the nacelle of the wind generator by means of two bearings.
Patent application WO04046582, like WO02079644, describes a turbine in which the multiplier unit is directly coupled to the hub, in this way doing without the rotor shaft and therefore transmitting the forces and moments generated by the blades to the nacelle by means of the bearings onto the multiplier unit.
None of the systems mentioned satisfactorily solves the requirements presented by high power wind turbines that the industry needs. This invention tries to satisfy these needs.